In a Long Term Evolution (LTE) system, data transmission between a base station and a terminal device is performed based on scheduling of the base station. Before receiving downlink data or sending uplink data, the terminal device receives scheduling information sent by the base station. The scheduling information may include a physical resource allocated to UE, for example, at least one of information about a time-frequency resource or information about a modulation and coding scheme configured for the UE. In addition, the base station may further add, to the scheduling information, information about a power control command (power control command) related to uplink transmission of the UE. The scheduling information and the information about the power control command are collectively referred to as downlink control information (DCI).
In the LTE system, a transmission time interval (TTI) is a length of one subframe, that is, 1 ms. The base station only needs to send one piece of DCI in one subframe, to instruct the terminal device to receive or send one data packet (Packet data) with a TTI of 1 ms.
In the LTE system, a latency is one of important factors affecting user experience. Constantly emerging new services, such as a service related to the Internet of Vehicles, impose higher requirements on a latency. An existing transmission mechanism based on a TTI of one subframe or an existing transmission mechanism based on a TTI of 1 ms cannot satisfy a service latency requirement of a user.